All butterfly valves are to be rated at 285 PSI minimum bubble tight shutoff and tested for flow retention at 315 PSI shut off. Certified test reports are to be available when requested.
Body:
Wafer and lug type bodies shall be of Cast Iron or Ductile Iron and shall have positive alignment features for installation between ANSI 125/150 flanges. The manufacturer shall offer valves with a neck length that allows for minimum of 2 inch of insulation. The operator mounting flange shall allow any operator furnished to be field repositioned without modification to three additional positions and without removing the valve from the line.
Disc:
Valve discs shall be of a streamlined design for low pressure drop and resistance to cavitation. Disc edge to be contoured and polished to minimize seating torque and seat wear. The valve disc shall be attached to the shaft by one or two precision taper pins to assure an absolute movement of the disc when the stem is rotated. Valves whose disc/shaft attachment lends itself to disc flutter will not be acceptable. Primary shaft sealing is to be accomplished by a flat area on the disc hub interfacing under compression with a flat area on the valve seat. A secondary seal consisting of an "O" ring will be used to back up the primary seal.
Shaft:
The valve shaft shall be one piece. Operator rotational forces shall be transmitted to the valve shaft through a key to assure positive movement of the shaft.
Seat:
Seat material shall be compatible with the line fluid with which it will be in contact. Valve seats shall be of the non-collapsing type utilizing a phenolic outer ring. The flange face portion of the seat is to protrude past the body face enough to form a flange seal. Seats which bunch or distort during opening or closing will not be acceptable. Valve seat design shall allow the disc to be in the fully closed position during installation between flanges.
Bearings:
The valve body shall have a minimum of three (3) reinforced Luberized Bronze sleeve type bearings which will amply support the valve shaft at the operator connection and at points immediately outboard of the seat. Valves utilizing the body material as a bearing will not be acceptable.
Valves and Actuators shall be supplied by the valve manufacturer as a single source. The valve manufacturer shall accept full responsibility during the warranty period for the valve, actuator and all accessories they contract to furnish.
Valves are to be Series 225 (formerly B-285) as manufactured by Center Line.
